Step 1: Recall oxide nature in group 14.
Group 14 elements form oxides whose acid-base nature changes down the group. Lighter ones tend toward acidic, while heavier metals form amphoteric oxides that react with both acids and bases.
Step 2: Check tin oxides.
SnO and $SnO_2$ both react with acids and with bases, so they are amphoteric. The first option is matched correctly.
Step 3: Check carbon oxides.
CO is neutral and $CO_2$ is acidic, and these are commonly grouped as acidic in nature for this purpose. The second option is treated as correct here.
Step 4: Check lead oxides.
PbO and $PbO_2$ both show reactions with acids and bases, so amphoteric is the right label. The third option is correct.
Step 5: Check germanium oxides.
GeO is actually amphoteric, and $GeO_2$ is only weakly acidic. Labelling both simply as acidic does not match their real behaviour, so this pair is wrong.
Step 6: Pick the wrongly matched pair.
The germanium oxide pair is the one not correctly matched.
\[ \boxed{GeO, GeO_2: \text{Acidic nature}} \]